How to Make It
Preheat oven to 350°F. Combine butter and vanilla in a large bowl. Add pretzels and toss to coat.
Whisk together sugar and cocoa powder in a small bowl. Add to pretzels and toss to coat. Transfer to 2 rimmed baking sheets and bake, rotating sheets halfway through, until dry to the touch, 12 to 15 minutes. Let cool completely on sheets.
Drizzle pretzels with white chocolate, then with semisweet chocolate. Scatter sprinkles over top, along with sea salt, if desired. Refrigerate until chocolate is set, about 10 minutes. Pretzels will keep in an airtight container at room temperature for up to 1 week.